Orphaned refugee children walk among the shelters at the Jungle camp at Calais in France.
Photograph: Chris Radburn/PA

The Home Office is facing fresh criticism after confirming it is yet to fill all the spaces it reserved for unaccompanied child refugees from Europe under the Dubs scheme.

Yvette Cooper, the chair of the Commons home affairs committee, described the government’s approach as “completely inadequate” after it set out its position in its formal response to a report published by the committee earlier this year.

Cooper also said her committee would hold fresh hearings on the subject in the future, saying that government claims to be serious about tackling modern slavery “look hollow” in the light of its unwillingness to help unaccompanied children at risk of trafficking on the continent.

In 2016, after defeats in the House of Lords, the government accepted an amendment to the immigration bill proposed by Lord Dubs requiring the Home Office to accept an unspecified number of unaccompanied child refugees from Europe for resettlement in the UK.

At the time it was expected that around 3,000 children would benefit from the scheme, but when the government announced details in February 2017 it said only 350 spaces would be available. That number was subsequently increased to 480.

On Friday, in its response to the home affairs committee’s report, the Home Office said the number of children who had arrived in the UK under the Dubs scheme was “over 200” and that Amber Rudd, the home secretary, has written to her counterparts in France, Greece and Italy inviting more referrals from eligible children.

To be eligible, children have to have arrived in Europe before March 2016 and it has to be in their best interests for them to come to the UK. Priority is supposed to be given to those deemed vulnerable, including at risk from trafficking.

In its response to the committee, the Home Office also said the total number of unaccompanied asylum-seeking children in local authority care in the UK was over 4,000 – around 10 times as many as may eventually be accepted under the Dubs scheme.

Dismissing the Home Office response as complacent, Cooper, a Labour MP, said ministers should be doing much more to take advantage of the spaces for unaccompanied child refugees that were available.

“Contrary to speedily delivering the Dubs scheme, less than half the places councils offered at the beginning of the year have been filled even though unaccompanied refugee children are spending another winter in camps or other unsuitable shelters in Greece and Italy,” she said.

“All the government’s commitments to tackle modern slavery look hollow when they are still resisting implementing a scheme to prevent teenagers being exploited and trafficked in Europe.

“This remains a policy failure by the home secretary and the committee will revisit this issue in the future.”

The government came up with 480 as the total number of children it could accept after consulting with local councils to see how many they could take.

The home affairs committee report earlier this year suggested that a further 4,000 places could be available if councils received appropriate funding from central government.

But the Home Office response on Friday said that this figure was wrong because it was based on the assumption that a threshold for the maximum number of child refugees any single authority is supposed to take could become a target for all of them to meet.